1. Field of the Invention
The present invention relates to an organic light-emitting apparatus used in a flat panel display or the like and a method of producing the same.
1. Description of the Related Art
In recent years, attention has been attracted to an organic light-emitting apparatus, which is a self-emission type device, as a flat panel display. The characteristics of an organic light-emitting device which constitutes an organic light-emitting apparatus are liable to be degraded due to moisture, oxygen or the like. The presence of even a small amount of moisture can result in peeling between an organic compound layer and an electrode layer, which becomes a cause of a dark spot. Therefore, such an organic light-emitting device is covered with an etching glass cover, its periphery is sealed with a sealing agent, and a desiccant is placed inside thereof such that moisture which intrudes through sealed surfaces is absorbed with the desiccant to secure the lifetime of the organic light-emitting device.
However, in order to realize a space-saving flat panel display utilizing a thin organic light-emitting apparatus, the space for a desiccant at the periphery of a light-emitting area needs to be eliminated to further reduce the thickness, and thus, a method of sealing an organic light-emitting apparatus which does not require a large amount of a desiccant is necessary. Therefore, solid sealing with a high-performance passivation layer for preventing intrusion of moisture or oxygen into an organic compound layer is required.
Generally, when a passivation layer is formed, in order to prevent the passivation layer from being formed on an external connection terminal for electrical connection to an electric circuit outside the organic light-emitting device, the external connection terminal and the like are covered with a plate-shaped area mask formed of a metal or the like. However, there has been a problem that deflection of a substrate constituting the organic light-emitting device or deflection of the area mask creates a gap between the substrate and the area mask to form a passivation layer also on the external connection terminal. Accordingly, a method which does not use an area mask has been required and proposed.
Japanese Patent Application Laid-Open No. 2002-151254 describes a method in which a masking tape is applied to a region including an external connection terminal, and after a passivation layer has been formed, the masking tape and the passivation layer are peeled off together. Further, there is also described a method in which an organic compound layer is formed in a region including an external connection terminal, and after a passivation layer has been formed, photoetching is carried out using ultraviolet light to peel off the organic compound layer and the passivation layer together.
Japanese Patent Application Laid-Open No. 2004-165068 describes a method in which a laser elimination layer is formed in a region including an external connection terminal, and after a passivation layer has been formed thereon, laser light is irradiated to remove the laser elimination layer and the passivation layer together.
However, when the passivation layer is peeled to be removed using a masking tape, photoetching, laser irradiation, or blasting, a minute crack, peeling, or the like is produced in a cross section of the passivation layer. These develop due to environment change for a long period of time to reach a light-emitting area, which ultimately impairs the moisture resistance of the passivation layer.
In particular, there are many cases where a passivation layer is formed of silicon nitride, silicon oxynitride, silicon oxide, or the like, and the film thickness is as large as 1 μm to several μm. When such a passivation layer is peeled to be removed, the occurrence rate of cracking is increased.
Further, while an organic light-emitting apparatus including a substrate with a thin-film transistor (TFT) has an organic planarization layer on the TFT, cracks are newly produced in a passivation layer formed on the organic planarization layer due to a temperature change or humidity change. On the other hand, cracks which already exist develop at a higher speed. More specifically, the organic planarization layer will expand and contract due to a change in temperature of the organic light-emitting device. Stress is applied to the organic planarization layer and to the passivation layer including an inorganic material when the organic planarization layer expands or contracts due to a difference in coefficient of expansion. Therefore, the passivation layer formed on the organic planarization layer which already has minute cracks therein yields to the thermal stress and produces new cracks, and the cracks develop with the elapse of time.